That particular package rate has changed quite a bit since I first booked it. It looks as though that package rate (if booked today) wouldn't be higher if it's two people instead of one. I've just checked the rate as a new booking and it doesn't change when it's one person or two in the room. I just can't add a second person by editing my booking online as then it wants to reprice to the changed (higher for one person or two) rate they're now showing rather than the lower rate for that package which I got.

Think we'll just both show up and hope it's OK. Thanks everyone.